Filesystem building method

ABSTRACT

To provide a technique whereby a plurality of types of storage media can be utilized in an efficient manner. A management apparatus includes a file manager that manages files within an integrated memory area that includes a first memory area composed of at least a part of the first type of storage medium and a second memory area composed of at least a part of the second type of storage medium. The file manager builds one filesystem on the integrated memory area, in consideration of a range of the first memory area and a range of the second memory area.

CROSS REFERENCE

The present application is based on, and claims priority from, JapaneseApplication No. 2005-265093 filed Sep. 13, 2005, the disclosure of whichis herein incorporated by reference.

BACKGROUND

The present invention relates to storage system technology.

Storage systems of a type connected directly to a network, termed NAS(Network Attached Storage) are in widespread use. The use of such astorage system allows a filesystem to be shared among clients via thenetwork, and enables the same file to be accessed by clients.

In recent years, there have been attempts to realize effective datautilization and efficient storage investment by storing data on storagemedia of optimal cost, depending on value of the data based on itsimportance or other consideration. This approach is termed informationlifecycle management (ILM). For example, data of relatively high valueis stored on an expensive FC (Fibre Channel) compatible hard disk, whiledata of relatively low value is stored on an inexpensive ATA compatiblehard disk. Note that, FC compatible hard disks are characterized byhigher reliability and faster access time than ATA compatible harddisks.

Where ILM is implemented using a plurality of types of storage media,such as an FC compatible hard disk and an ATA compatible hard disk,typical practice is to establish a logical unit for each type of storagemedium, and to build a filesystem for each logical unit. That is, whenimplementing ILM, a plurality of filesystems are built for each type ofstorage medium.

Employing existing technology, it is also possible to establish onelogical unit for the plurality of types of storage media, and to buildone filesystem on the logical unit. However, in this case, it becomesdifficult to deploy ILM appropriately, that is, to utilize the pluralityof types of storage media in an efficient manner.

SUMMARY

The present invention solves the above-described problem of conventionaltechnology, and there is need to provide a technique whereby a pluralityof types of storage media can be utilized in an efficient manner, evenin a case where one filesystem is built on the plurality of types ofstorage media.

At least part of the above and the other related objects is attained byan apparatus of the present invention. The apparatus is a managementapparatus for managing a first type of storage medium and a second typeof storage medium. The management apparatus comprises: a file managerfor managing files within an integrated memory area that includes afirst memory area composed of at least a part of the first type ofstorage medium and a second memory area composed of at least a part ofthe second type of storage medium. The file manager builds onefilesystem on the integrated memory area, in consideration of a range ofthe first memory area and a range of the second memory area.

Where a filesystem is built on an integrated memory area withoutconsideration to the range of the first memory area and the range of thesecond memory area, there is a possibility that a file is storedspanning the first memory area and the second memory area. However, withthis apparatus, a filesystem is built on the integrated memory area withconsideration to the range of the first memory area and the range of thesecond memory area. Thus, a file will not be stored spanning the firstmemory area and the second memory area, and files are stored in fileunits in the first memory area or the second memory area within onefilesystem. As a result, it is possible for the first type of storagemedium and the second type of storage medium to be utilized effectively.

In the above apparatus, it is preferable that the file managerestablishes a plurality of group areas within the integrated memoryarea. It is preferable that each of the plurality of group areas doesnot span the first memory area and the second memory area.

In this way, by establishing group areas that do not span the firstmemory area and the second memory area in advance, a file will not bestored spanning the first memory area and the second memory area.

In the above apparatus, the file manager may establish a first type ofgroup area in the first memory area, wherein in the first type of grouparea metadata is stored. And the file manager may establish a secondtype of group area in the second memory area, wherein in the second typeof group area metadata is not stored.

When accessing a file, the metadata is retrieved. By employing abovearrangement, when retrieving the metadata, it suffices to search thefirst memory area only, as a result of which it is possible to quicklyaccess the intended file.

This advantage is particularly notable in instances where the first typeof storage medium can be accessed faster than the second type of storagemedium.

Alternatively, in the above apparatus, the file manager may establish agroup area in each of the first memory area and the second memory area,wherein in the group area metadata is stored.

In this arrangement, the per-bit cost entailed in storage of metadatacan be reduced, as compared to the case where the first type of storagemedium is more expensive than the second type of storage medium, andmetadata is stored in first memory area only.

Alternatively, in the above apparatus, the file manager may establishwithin the integrated memory area a group area that spans the firstmemory area and the second memory area. And the file manager may buildthe filesystem such that actual data of a file is stored in the firstmemory area or the second memory area, based on area informationindicating the range of the first memory area and the range of thesecond memory area.

In this arrangement, even where a group area is established spanning thefirst memory area and the second memory area, a file will not be storedspanning the first memory area and the second memory area.

In the above apparatus, it is preferable that the file manager furtherbuilds the filesystem such that metadata is stored in the first memoryarea and is not stored in the second memory area, based on the areainformation.

By employing above arrangement, when retrieving the metadata, itsuffices to search the first memory area only, as a result of which itis possible to quickly access the intended file.

The present invention is also directed to a storage system including:the first type of storage medium; the second type of storage medium; andthe above management apparatus.

It should be noted that the present invention may be actualized by adiversity of applications such as a management apparatus for managingdifferent types of storage media, a storage system including themanagement apparatus, a network system including the storage system, amethod for managing different types of storage media in these devices,computer programs that attain these methods or functions of thesedevices, recording media in which such computer programs are recorded,and data signals that include such computer programs and are embodied incarrier waves.

These and other objects, features, aspects, and advantages of thepresent invention will become more apparent from the following detaileddescription of the preferred embodiments with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a simplified configuration of a network system;

FIG. 2 shows internal configuration of a storage system 100;

FIG. 3 shows contents of a volume management table TB prepared inadvance;

FIG. 4 shows internal configuration of a management server 200;

FIG. 5 is a flowchart depicting the procedure for creating a filesystem;

FIG. 6 shows structure of the filesystem created on the first LU (LUN=0)in Step S110 (FIG. 5);

FIG. 7 shows content of a volume management table TB obtained when theprocess of FIG. 5 is completed;

FIG. 8 shows structure of a filesystem on the first LU (LUN=0);

FIG. 9 is a flowchart depicting the procedure when creating a new filewithin an LU;

FIG. 10 is a flowchart depicting the procedure for transferring a filewithin an integrated LU;

FIG. 11 shows structure of the filesystem before and after the filetransfer process;

FIGS. 12(A) and 12(B) are illustrations depicting in model form thefilesystem of the first embodiment and a filesystem of a comparativeexample, respectively;

FIG. 13 shows structure of a filesystem on the first LU (LUN=0) in thesecond embodiment;

FIG. 14 is a flowchart depicting the procedure for transferring a filewithin an integrated LU in the second embodiment;

FIG. 15 shows structure of the filesystem before and after the filetransfer process in the second embodiment;

FIG. 16 shows structure of a filesystem on the first LU (LUN=0) in thethird embodiment;

FIG. 17 is a flowchart depicting the procedure for creating a new filein an LU;

FIG. 18 is a flowchart depicting the procedure when transferring a filewithin an integrated LU in the third embodiment; and

FIG. 19 shows structure of the filesystem before and after the filetransfer process in the third embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Embodiments of the present invention are discussed below based onexamples in the following order.

-   A. First Embodiment:    -   A-1. Configuration of Network System:        -   A-1-1. Internal Configuration of Storage System:        -   A-1-2. Internal Configuration of Management Server:    -   A-2. Creation of Filesystem:    -   A-3. Structure of Filesystem on Integrated Memory Area:    -   A-4. Creation of New File:    -   A-5. Transferring File:-   B. Second Embodiment:-   C. Third Embodiment:

A. First Embodiment

A-1. Configuration of Network System:

FIG. 1 shows a simplified configuration of a network system. The networksystem comprises a storage system (NAS) 100, a management server 200, amanagement terminal 300, and a plurality of clients 400. Each device isconnected to an IP based network NW, with communication among devicestaking place according to TCP/IP.

The storage system 100 comprises a file server (also referred to as anNAS head) 110, and a storage unit 130. In this embodiment, the fileserver 110 and the storage unit 130 are housed in different cases, butcould instead be housed in a common case.

A-1-1. Internal Configuration of Storage System:

FIG. 2 shows the internal configuration of the storage system 100. Asnoted, the storage system 100 comprises the file server 110 and thestorage unit 130. The storage unit 130 comprises a disk array controller140 and a disk array unit 160. Note that, the file server 11 and thedisk array controller 140 may be the same device (e.g. the sameprocessor).

The file server 110 comprises a CPU 112, a memory 114 such as ROM andRAM, a network interface (IF) 116, and a storage interface (IF) 118. Thenetwork interface 116 is an interface for communicating with externaldevices through the network NW, and the storage interface 118 is aninterface for communicating with the storage unit 130.

In the memory 114 are stored a computer program that functions as aprotocol controller 122, a computer program that functions as a firstconfiguration manager 124, and a computer program that functions as afilesystem controller 126. Also in the memory 114, a cache area 128 fortemporary storage of data in transfer is provided.

The protocol controller 122 is a program executed by the CPU 112, forexecuting various processes in accordance with protocol, in order tocarry out communication with external devices via the network NW.

The first configuration manager 124 is a program executed by the CPU112, for creating a filesystem on one or more logical units establishedin the disk array unit 160, and managing associations between logicalunits and filesystems.

The filesystem controller 126 is a program executed by the CPU 112, forcontrolling various processes such creating or moving files. Forexample, the filesystem controller 126 modifies the content of thefilesystem in conjunction with creation or movement of a file.

The disk array controller 140 comprises a CPU 142, a memory 144 such asROM and RAM, a host interface (IF) 146, and a drive interface (IF) 148.The host interface 146 is an interface for communicating with the fileserver 110 that functions as the host of the storage unit 130, and thedrive interface 148 is an interface for driving the disk array unit 160to input/output data.

In the memory 144 are stored a computer program that functions as ainput/output processor 152, and a computer program that functions as asecond configuration manager 154. Also in the memory 144, a cache area156 for temporary storage of data in transfer is provided.

The input/output processor 152 processes I/O commands given from thefile server 110 via the host IF 146. For example, in accordance with aread command or a write command, the input/output processor 152 executesa data read or write process on the disk array unit 160.

The second configuration manager 154 is a program executed by the CPU142, for establishing logical units for the disk array unit 160, andmanaging associations between logical units and actual disks (storagemedia). The second configuration manager 154 also creates in the diskarray unit 160 a volume management table TB (described later) indicatingthe aforementioned associations.

The disk array unit 160 comprises a disk array composed of a pluralityof storage media (e.g. a plurality of hard disk drives). The disk arraymay also be of RAID configuration. In this embodiment, two types of harddisk are used, namely, expensive FC compatible hard disks andinexpensive ATA compatible hard disks. Hereinafter, FC compatible harddisks are also referred to as “first type media,” and ATA compatiblehard disks are also referred to as “second type media.”

Typically, the disk array unit 160 is partitioned into logical units(LU) for use. In FIG. 2, one system LU and three data LUs have beenprepared. The first data LU is an integrated memory area (integrated LU)that includes a memory area composed of part of a first type medium (FC)and a memory area composed of part of a second type medium (ATA); it isassigned a logical unit number (LUN) of “0.” The second LU is a memoryarea composed of part of a first type medium (FC) and is assigned a LUNof “1.” The third LU is a memory area composed of part of a second typemedium (ATA), and is assigned a LUN of “2.” In this embodiment, thesystem LU is a memory area composed of part of a first type medium (FC).As illustrated, a volume management table TB is stored in the system LU.Note that, each memory area may be composed of all or part of a singledisk of the corresponding type, or composed of multiple disks of thecorresponding type.

The volume management table TB is created in advance by the networksystem administrator, from the management terminal 300. Specifically, inaccordance with instructions by the administrator, the secondconfiguration manager 154 of the storage unit 130 creates the volumemanagement table TB.

FIG. 3 shows the contents of the volume management table TB prepared inadvance. This volume management table TB is created prior to creation ofa filesystem on each data LU. As illustrated, information for each dataLU is contained in the volume management table TB. Specifically, in thevolume management table TB, for each type of medium making up a memoryarea, the type of medium making up the memory area, and the startingaddress and ending address of the memory area are established.

For example, as described with reference to FIG. 2, the first LU (LUN=0)includes a memory area composed of a first type medium (FC) and a memoryarea composed of a second type medium (ATA). Thus, in the volumemanagement table TB, with regard to the first LU, “FC” is registered asthe type of medium of the first memory area, and a starting address of“0” and an ending address of “999” of the first memory area areregistered. “ATA” is registered as the type of medium of the secondmemory area, and a starting address of “1000” and an ending address of“1999” of the second memory area are registered.

Similarly, the second LU (LU=1) includes a memory area composed of afirst type medium (FC) only. Thus, in the volume management table TB,with regard to the second LU, “FC” is registered as the type of mediumof the first memory area, and a starting address of “0” and an endingaddress of “3000” of the first memory area are registered. The third LU(LU=2) includes a memory area composed of a second type medium (ATA)only. Thus, in the volume management table TB, with regard to the thirdLU, “ATA” is registered as the type of medium of the first memory area,and a starting address of “0” and an ending address of “5000” of thefirst memory area are registered.

Note that, the file server 110 of this embodiment corresponds to amanagement apparatus in the present invention, and the firstconfiguration manager 124 and the filesystem controller 126 correspondto a file manager in the present invention.

A-1-2. Internal Configuration of Management Server:

FIG. 4 shows the internal configuration of the management server 200.The management server 200 comprises a CPU 202, a memory 204 such as ROMand RAM, and a network interface (IF) 206. The network interface 206 isan interface for communicating with external devices via the network NW.

In the memory 204 are stored a computer program that functions as aprotocol controller 212, and a computer program that functions as a filedistribution controller 214.

The protocol controller 212, like the protocol controller 122 of FIG. 2,is a program executed by the CPU 202, for executing various processes inaccordance with protocols, in order to carry out communication withexternal devices via the network NW.

The file distribution controller 214 is a program executed by the CPU202, for determining which type of medium should be used for storing afile that is to be stored in the integrated memory area (integrated LU)in the storage system 100. Specifically, in the event of a query fromthe file server 110, the file distribution controller 214 decides on astorage destination medium for a file in the integrated LU, inaccordance with a distribution rule established previously by theadministrator. Distribution rules can be established utilizing variousinformation (attributes) belonging to files, such as, file name, lastupdate time of file, file size, file creator, or the like. Distributionrules can also prescribe a storage destination medium type depending onthe value of a file. Note that, distribution rule information is storedin the memory of the management server 200.

For example, if a file name includes a predetermined text string, iflast update time of file is after a predetermined time, if file sizeexceeds a predetermined size, if the name of the file creator matches aname registered in a list, or the like, the file distribution controller214 will deem the file to have high value, and will select a medium ofthe first type (FC) as the file storage destination.

Distribution rules can utilize not only various information (attributes)belonging to files, but also other information that does not belong tofiles. For example, the period of time for which a file is stored in thestorage system 100 could be utilized. In this case, it would beacceptable, for example, to select a medium of the first type (FC),which requires a relatively short time for write operations, as the filestorage destination during time periods when large numbers of files aresaved (e.g. during business hours on weekdays), while selecting a mediumof the second type (ATA), which requires a relatively long time forwrite operations, as the file storage destination during time periodswhen few files are saved (e.g. times other than business hours onweekdays).

A-2. Creation of Filesystem:

FIG. 5 is a flowchart depicting the procedure for creating a filesystem.In Step S102, the administrator, using the management terminal 300,instructs the file server 110 to create a filesystem on a target LU.During this process, via the management terminal 300, the administratorsends to the file server 110 information specifying whether or notmetadata is permitted to be stored in a memory area. Where a fast andexpensive FC and a slow and inexpensive ATA are to be integrated, theadministrator may decide whether or not metadata is permitted to bestored based on the following consideration. Specifically, if it isdesired to “store metadata to the FC exclusively, for faster accessdespite higher cost,” metadata will be stored to the FC exclusively. Onthe other hand, if it is desired to “store metadata to both the FC andthe ATA, to lower the cost despite lower performance,” metadata will bestored to the FC and the ATA. On the basis of the decision, theadministrator then creates information specifying whether or notmetadata is permitted to be stored.

In Step S104, the first configuration manager 124 in the file server 110that has received the instruction queries the second configurationmanager 154 in the storage unit 130, regarding the type of mediumconstituting the target LU. At this time, the second configurationmanager 154 refers to the volume management table TB, and notifies thefirst configuration manager 124 of the type of medium constituting thetarget LU.

In Step S106, the first configuration manager 124, on the basis of thenotification by the second configuration manager 154, determines whetherthe target LU is composed of multiple types of media. If the target LUis composed of multiple types of media (e.g. where the target LU is thefirst LU (LUN=0)), the routine proceeds to Step S108. On the other hand,if the target LU is composed of a single type of medium rather thanmultiple types of media (e.g. where the target LU is the second LU(LUN=1) or the third LU (LUN=2)), the routine proceeds to Step S112.

In Step S108, the first configuration manager 124 decides whether usages(settings) for each type of medium have been specified from themanagement terminal 300. In this embodiment, usages to the effect thatmetadata is stored to the first type of medium, but is not stored to thesecond type of medium, are specified. Note that, metadata includesdirectory information, and an inode that contains a data pointerindicating the storage location of the actual data of a file. Metadatawill be discussed further later.

Where a usage has been specified, the routine proceeds to Step S110. Onthe other hand, no usage has been specified, the routine proceeds toStep S112.

In Step S110, the first configuration manager 124 creates in the targetLU (integrated LU) a block group on the basis of the specified usages.At this time, the first configuration manager refers to the volumemanagement table TB (FIG. 3), and creates the block group inconsideration of the address range of each memory area. By so doing, afilesystem is created within the target LU. Note that, the block groupcorresponds to a group area in the present invention.

FIG. 6 shows the structure of the filesystem created on the first LU(LUN=0) in Step S110 (FIG. 5).

Where a filesystem is created on an LU, typically, one or more blockgroups are created for the LU regardless of whether or not the LU iscomposed of multiple types of media. Thus, where an LU is composed ofmultiple types of media, there is a possibility that a block group iscreated spanning two or more types of media.

However, in this embodiment, block groups are created with considerationto the address range of each memory area, on a per-memory area basis, inother words, on a per-medium type basis. Thus, each block group iscreated within a single medium, without spanning two or more types ofmedia.

Specifically, in this embodiment, as depicted in FIG. 6, three blockgroups are created in the first memory area composed of a first typemedium (FC), and three block groups are created in the second memoryarea composed of a second type medium (ATA). Each block group is createdwithout spanning the first type of medium and the second type of medium,in other words, without spanning the first memory area and the secondmemory area. Note that, block groups may be created for each ofpredetermined sizes (capacity), or created in predetermined number.

As depicted in FIG. 6, the arrangement of block groups created in thefirst memory area (hereinafter also termed “first type block groups”)differs from the arrangement of block groups created in the secondmemory area (hereinafter also termed “second type block groups”).

Specifically, the first type block groups have the typical arrangement,including block group placement information, an inode counter, an inodelist, a free data block counter, a free data block list, and a datablock. The second type block groups have an arrangement similar to thatof the first type block groups, but do not include an inode counter andan inode list. While metadata is stored in the data block of first typeblock group, metadata is not stored in the data block of second typeblock group. Each of the aforementioned elements included in the blockgroups will be discussed later.

The arrangement of block groups created in the first memory area differsfrom the arrangement of block groups created in the second memory areain this way, due to different usages. Specifically, in this embodiment,in Step S108, there are specified usages to the effect that metadata isstored in the first type medium, but not in the second type medium.Thus, in this embodiment, in the first memory area composed of the firsttype medium, the first type of block group including an inode counterand an inode list and permitting metadata to be stored is created. Inthe second memory area composed of the second type medium, on the otherhand, the second type of block group not including an inode counter andan inode list and not permitting metadata to be stored is created.

The description now returns to FIG. 5. In Step S112 (FIG. 5), the firstconfiguration manager 124 creates block groups within the target LU, bythe usual method, i.e. without any awareness of the type of medium. Inthis embodiment, one or more block groups are created in the second LU(LUN=1) and the third LU (LUN=2), respectively. Each block group is thefirst type of block group including an inode counter and an inode listand capable of storing metadata is created.

In Step S114, the first configuration manager 124 causes the secondconfiguration manager 154 to update the volume management table TB.

FIG. 7 shows the content of the volume management table TB obtained whenthe process of FIG. 5 is completed. While FIG. 7 is similar to FIG. 3,whether or not metadata is permitted to be stored is added to the table,for each type of medium constituting a memory area.

In FIG. 7, memory areas set to allow storage of metadata are assignedthe symbol “O”, and memory areas set to disallow storage of metadata areassigned the symbol “X.”

For example, the first LU (LUN=0) is composed of a first type of medium(FC) and a second type of medium (ATA). Thus, on the basis of the usagesspecified in Step S108, the first memory area composed of the first typeof medium (FC) is set to allow storage of metadata, while the secondmemory area composed of the second type of medium (ATA) is set todisallow storage of metadata. Each of the second LU (LUN=1) and thethird LU (LUN=2) is composed of the one type of medium. Accordingly,each of memory areas within the second LU and the third LU is set toallow storage of metadata.

A-3. Structure of Filesystem on Integrated Memory Area:

FIG. 8 shows the structure of a filesystem on the first LU (LUN=0).While FIG. 8 is similar to FIG. 6, in FIG. 8, an illustration of datainside data blocks has been added. In FIG. 8, files have already beenstored.

As discussed previously, each of the first and second types of blockgroup contains block group placement information, a free data blockcounter, a free data block list, and a data block. The first type ofblock group further includes an inode counter and an inode list.

Both the first and second types of block group contain a data block, butthe data block in the first type of block group and the data block inthe second type of block group contain different information.Specifically, the data block in the first type of block group includesmetadata composed of directory information and inodes, and a data areain which the actual data of file is stored, whereas the data block inthe second type of block group includes a data area only.

Directory information is information that registers associations betweenfile names and inode numbers. Note that, in FIG. 8, one directory hasbeen created, but several directories may be created.

Each inode includes information of various kinds such as file size, lastupdate time, and data pointer. The data pointer indicates the location(address) of the data area where the actual data of file is stored.

For example, in FIG. 8, in “block group 1” in the first memory area,“file A” is associated with “inode1”, and the data pointer of “inode1”identifies the location of the data area in which the data making up“file A” (termed “actual data”) is stored. Similarly, in “block group1”, “file B” is associated with “inode2”, and the data pointer of“inode2” identifies the location of the data area in which the actualdata of “file B” is stored. In FIG. 8, the actual data of “file A” isstored in “block group 1” in the first memory area, and the actual dataof “file B” is stored in “block group 4” in the second memory area.

In this way, in this embodiment metadata composed of directoryinformation and inodes is only stored in the first memory area, whilethe actual data of file is stored in either of two memory areas,depending on the value of the data.

The block group placement information is information indicating therange (address) of the block group to which it pertains.

The free data block counter is a counter for assigning numberssequentially to areas when storing inodes and actual data of files infree areas within a data block. The free data block list containsinformation indicating ranges (addresses) of free areas in a data block.

The inode counter is a counter for assigning numbers sequentially toinodes. The inode list contains information indicating locations(addresses) of inodes in a data block.

In FIG. 8, since the file is already stored, metadata is stored in thedata block of the first type of block group, but at the time immediatelyafter the process of FIG. 5, the metadata is not stored. In the processof FIG. 5, only a root directory is created in the data block within thefirst type of block group.

When creating block groups in FIG. 5, initialization of the block groupsis carried out at the same time. For example, the address range of theblock group is registered in its block group placement information, andthe values of the inode counter and the free data block counter are setto their initial values.

A-4. Creation of New File:

FIG. 9 is a flowchart depicting the procedure when creating a new filewithin an LU.

In Step S202, the file server 110 receives a target file for storagefrom a client 400. Specifically, the user of the client 400, whileconfirming the screen display on the computer (client 400), instructsthat a target file be stored to a target disk connected to the network.At this time, the client 400 sends to the file server 110 diskinformation indicating the target disk, and the target file. On thebasis of the received disk information, the filesystem controller 126 inthe file server 110 then identifies the LU where the received file is tobe stored (storage destination LU).

In Step S203, the filesystem controller 126 refers to the volumemanagement table TB and decides whether the storage destination LU iscomposed of multiple types of media. If the storage destination LU iscomposed of multiple types of media (e.g. the storage destination LU isthe first LU (LUN=0)), the routine proceeds to Step S204. If the storagedestination LU is not composed of multiple types of media (e.g. thestorage destination LU is the second LU (LUN=1) or the third LU(LUN=2)), the routine proceeds to Step S208.

In Step S204, the filesystem controller 126 queries the managementserver 200 regarding the type of medium where the file is to be stored(storage destination medium). During this process, the filesystemcontroller 126 sends to the management server 200 information regardingthe target file as well. At this time, the file distribution controller210 in the management server 200, on the basis of information such asfile name or last update time of the received target file, determinesthe type of storage destination medium in accordance with a distributionrule, and notifies the filesystem controller 126.

In Step S206, the filesystem controller 126 decides whether it ispossible to store metadata in the storage destination memory areacorresponding to the storage destination medium specified in Step S204.This decision is made be referring to the volume management table TB(FIG. 7). If it is possible to store metadata in the storage destinationmemory area (e.g. where the storage destination memory area is the firstmemory area composed of the first type of medium (FC)), the routineproceeds to Step S208. On the other hand, if it is not possible to storemetadata in the storage destination memory area (e.g. where the storagedestination memory area is the second memory area composed of the secondtype of medium (ATA)), the routine proceeds to Step S210.

In Step S208, the filesystem controller 126 creates an inode, and writesthe actual data of the file to the storage destination memory area (e.g.the first memory area of FIG. 8). Note that, the address range of thestorage destination memory area is identified by referring to the volumemanagement table TB.

Specifically, first, one block group (e.g. “block group 1” in FIG. 8) isselected as the target block group, from among one or more block groupscreated in the storage destination memory area. Where two or more blockgroups are present, the target block group is selected sequentially incyclical fashion from among the two or more blocks by the filesystemcontroller 126.

Next, a new inode area is acquired from the free data block list in thetarget block group of the storage destination memory area, and theaddress of the new inode area is registered in the inode list. Whenacquiring the new inode area, a new inode number is determined by theinode counter, and the value of the inode counter is incremented by 1.Also, when acquiring the new inode area, the value of the free datablock counter is incremented by 1.

Next, a new data area is acquired from the free data block list in thetarget block group of the storage destination memory area, and theaddress of the new data area is registered in the data pointer of theinode. When acquiring the new data area, the value of the free datablock counter is incremented by 1. The actual data of the file is thenwritten to the new data area.

For example, in Step S208, if “file A” is stored to the first memoryarea composed of the first type of medium (FC) of the first LU (LUN=0),as shown in FIG. 8, “inode1” is created in the first memory area, andthe actual data of “file A” is stored in the first memory area. In FIG.8, during saving of “file A”, “block group 1” is selected as the targetblock group.

On the other hand, in Step S210, the filesystem controller 126 createsan inode in another memory area capable of storing metadata (e.g. thefirst memory area in FIG. 8) different from the storage destinationmemory area (e.g. the second memory area of FIG. 8), and writes theactual data of the file to the storage destination memory area. Notethat, the address range of the storage destination memory area and theaddress range of this other memory area are identified by referring tothe volume management table TB.

Specifically, first, one block group (.e.g. “block group 1”) is selectedas a first target block group, from among one or more block groupscreated in the other memory area (e.g. the first memory area in FIG. 8).Also, one block group (e.g. “block group 4”) created in the storagedestination memory area (e.g. the second memory area in FIG. 8) isselected as a second target block group.

Then, in the first target block group of the other memory area, a newinode area is acquired from the free data block list, and the address ofthe new inode area is registered in the inode list.

Next, in the second target block group of the storage destination memoryarea, a new data area is acquired from the free data block list, and theaddress of the new data area is registered in the data pointer of theinode. The actual data of the file is then written to the new data area.

For example, in Step S210, if “file B” is stored to the second memoryarea composed of the second type of medium (ATA) of the first LU(LUN=0), as shown in FIG. 8, “inode2” is created in the second memoryarea, and the actual data of “file B” is stored in the second memoryarea. In FIG. 8, during saving of “file B”, “block group 1” is selectedas the first target block group, and “block group 4” is selected as thesecond target block group.

In Step S212, the filesystem controller 126 registers the associationbetween file name and inode number in the directory information of thedirectory in which the target file is created.

For example, if in Step S208 “file A” is stored to the first memory areacomposed of the first type of medium (FC) of the first LU (LUN=0), asshown in FIG. 8, the association of “file A” and “inode1” is registeredin the directory information in the first memory area. If in Step S210“file B” is stored to the second memory area composed of the second typeof medium (ATA) of the first LU (LUN=0), as shown in FIG. 8, theassociation of “file B” and “inode2” is registered in the directoryinformation in the first memory area.

In Step S214, the filesystem controller 126 notifies the client 400 thatnew file creation has been completed normally. With this, the new filecreation process is complete.

If the storage destination LU is composed of one type of medium (e.g.the storage destination LU is the second LU (LUN=1) or the third LU(LUN=2), the process of Step S208 will be executed. And then, an inodewill be created and the actual data of the file will be written in thestorage destination memory area.

A-5. Transferring File:

FIG. 10 is a flowchart depicting the procedure for transferring a filewithin the integrated LU. Transferring a file within the integrated LUis needed because the value of the file changes. For example, it ispossible that even if a file had a high value when the file was stored,the file currently has a lower value. Conversely, it is also possiblethat even if a file had a low value when the file was stored, the filecurrently has a higher value. Also, in certain instances thedistribution rule belonging to the file distribution controller 214 inthe management server 200 may have changed between the time that thefile was stored, and the current time.

In Step S302, the file server 110 receives from the management server200 the target file to be transferred (moved), the type of the transfersource medium, and the type of the transfer destination medium. The typeof transfer source medium is the type of the medium in which the targetfile to be transferred is stored, and the type of transfer destinationmedium is the type of the medium to which the target file is to bestored. Note that, the occasion for the management server 200 to sendinformation such as target files for transfer (the occasion for themanagement server 200 to check the filesystem) may be an off-peakperiod, such as nights or non-working days.

Specifically, the file distribution controller 210 in the managementserver 200, while referring to the volume management table TB, checksthe filesystem in the storage system 100, and inquires whether files inthe integrated LU composed of multiple types of media have been storedaccording to the distribution rule. The file distribution controller 210then determines any file that does not match the distribution rule to bea target file for transfer, and identifies the type of transfer sourcemedium of the file. The file distribution controller 210 also determinesthe type of transfer destination medium, in accordance with thedistribution rule.

For example, a file of low value stored in the first memory areacomposed of the first type of medium (FC) of the first LU (LUN=0) ofFIG. 8 does not match the distribution rule, and is determined as atarget file for transfer, and the first type of medium (FC) isidentified as the transfer source medium. In accordance with thedistribution rule, the second type of medium (ATA) is designated as thetransfer destination medium.

In Step S304, the filesystem controller 126 writes to the transferdestination memory area the actual data of the file targeted fortransfer, and modifies the contents of the inode corresponding to thefile targeted for transfer. Note that, the address range of the transferdestination memory area is identified by referring to the volumemanagement table TB.

Specifically, first, one block group is selected as the target blockgroup, from among one or more block groups created in the transferdestination memory area.

Next, in the target block group of the transfer destination memory area,a new data area is acquired from the free data block list. Also, theaddress indicated by the data pointer of the inode corresponding to thetarget file is changed from the address of the former data area, to theaddress of the new data area. Where the transfer destination memory areais the first memory area of FIG. 8, the inode corresponding to thetarget file is included in the transfer destination memory area, whereasif the transfer destination memory area is the second memory area ofFIG. 8, it is included in the transfer source memory area (i.e. thefirst memory area of FIG. 8).

Then, the actual data of the file for transfer is read out from theformer data area in the transfer source memory area, and written to thenew data area in the transfer destination memory area. Note that, theaddress of the former data area in which the actual data of the targetfile for transfer has been stored is identified by means of referring tothe data pointer of the inode that corresponds to the file name andindicates address before transfer process.

In Step S310, the filesystem controller 126 frees up the former dataarea of the transfer source memory area, in which the actual data of thetarget file for transfer remains stored. Specifically, in the blockgroup containing the former data area, the former data area is added asthe free area to the free data block list. By so doing, it becomespossible to write other data to the former data area.

In Step S312, the filesystem controller 126 notifies the filedistribution controller 210 in the management server 200 that filetransfer has completed normally. With this, the file transfer process iscomplete.

Reception of the type of transfer source medium in Step S302 may beomitted. Also, where the integrated LU is composed of two types ofmedia, it is possible to omit reception of the type of transferdestination medium. In this case, the filesystem controller 126 needonly receive from the file distribution controller 210 within themanagement server 200 the information of the target file for transfer,and to transfer the target file for transfer to a medium of differenttype.

FIG. 11 shows the structure of the filesystem before and after the filetransfer process. FIG. 11 is similar to FIG. 8, except that a diagram ofthe data block interior after the transfer process is added.

In FIG. 11, “file A” is being transferred from the first memory areacomposed of the first type of medium (FC) to the second memory areacomposed of the second type of medium (ATA). After the transfer process,a new data area storing the actual data of “file A” is established inthe second memory area, and the former data area where the actual dataof “file A” was stored previously is released from the first memoryarea. Also, the address indicated by the data pointer of “inode1” ismodified from the address of the former data area to the address of thenew data area. Note that, the directory information is not modified.

Similarly, where “file B” is transferred from the second memory areacomposed of the second type of medium (ATA) to the first memory areacomposed of the first type of medium (FC), after the transfer process, anew data area storing the actual data of “file B” is established in thefirst memory area, and the former data area where the actual data of“file B” was stored previously is released from the second memory area.Also, the address indicated by the data pointer of “inode2” is modifiedfrom the address of the former data area to the address of the new dataarea. Note that, the directory information is not modified.

In a preferred embodiment, the new data area for storing the actual dataof “file B” may be established in “block group 1” where “inode 2” isstored. By so doing, since it is highly likely that “inode2”corresponding to “file B” and new data area storing the actual data of“file B” are situated in relatively close physical location, “file B”can be read out relatively fast. However, the new data area storing theactual data of “file B” may instead be established in another blockgroup where “inode2” is not stored (e.g. in “block group 2” or “blockgroup 3”). In this case, the address indicated by the data pointer of“inode2” may be modified to the address of the new data area establishedwithin the other block group.

As discussed above, in this embodiment, since metadata is only stored inthe first memory area composed of the first type of medium (FC), when afile is transferred, the metadata relating to the file need only bemodified, without being created anew.

As described hereinabove, in this embodiment, one filesystem is built onan integrated LU that includes a first memory area composed of part ofthe first type of medium (FC) and a second memory area composed of partof the second type of medium (ATA). Specifically, a plurality of blockgroups are established within the integrated LU, such that each blockgroup does not span the first memory area and second memory area. Thatis, in this embodiment, block groups are established with considerationto the range of the first memory area and the range of the second memoryarea. Thus, during creation of a new file or file transfer (migration),the actual data of the file is not stored spanning the first memory areaand the second memory area (in other words, spanning the first type ofmedium and the second type of medium), and within one filesystem filesare distributed to the first memory area or second memory area, in fileunits. Accordingly, files can be stored to the appropriate type ofmedium depending on their value, and as a result it is possible toutilize a plurality of types of media efficiently.

Further, in this embodiment, since an integrated LU is established intwo memory areas and one filesystem is built on the integrated LU,capacity management can be carried out more readily, compared with thecase where two LUs are established in two memory areas, and twofilesystems are built in the two memory areas. This is because where onefilesystem is built, it is sufficient to check capacity targeting theone filesystem only, whereas if two filesystems are built, it isnecessary to check capacity targeting both filesystems.

When accessing any file, the metadata is retrieved. In this embodiment,metadata is stored only in the first memory area. Thus, in thisembodiment, when retrieving metadata, it is sufficient to search thefirst memory area only, and as a result it is possible to quickly accessthe intended file.

In particular, in this embodiment, metadata is stored only in the firstmemory area composed of the first type of medium (FC), which can beaccessed faster than the second type of medium (ATA). Thus, in thisembodiment, there is the advantage that the location of the actual dataof a file can be identified quickly, as compared to the case wheremetadata is stored in both the first memory area composed of the firsttype of medium and the second memory area composed of the second type ofmedium.

By the way, where metadata is stored in only one of the memory areas,and individual filesystems are built on both memory areas, it isdifficult to copy (remote copy) data to another LU, in filesystem units.With this embodiment, however, since one filesystem is built on anintegrated LU, data can readily be copied in filesystem units, asdiscussed hereinafter.

FIGS. 12(A) and 12(B) are illustrations depicting in model form thefilesystem of the first embodiment and a filesystem of a comparativeexample, respectively.

In this embodiment, as depicted in FIG. 12(A), an integrated LU isestablished in the first memory area composed of the first type ofmedium (FC) and the second memory area composed of the second type ofmedium (ATA), with a one filesystem built on the integrated LU. Metadatais only stored in the first memory area.

In the comparative example, on the other hand, as depicted in FIG.12(B), a first LU is established in the first memory area composed ofthe first type of medium (FC), and a second LU is established in thesecond memory area composed of the second type of medium (ATA). Twofilesystems are built on the two LUs. Metadata is only stored in thefirst memory area.

Thus, in the comparative example, where the actual data of a file isstored in the second memory area (second LU), it is necessary for thedata pointer of the inode in the metadata to include the LUN of thesecond LU.

Thus, where data is to be copied in filesystem units, assuming forexample that only the data in the second LU is to be copied to anotherLU, it is necessary to modify the LUN contained in the data pointer ofthe inode. Thus, it is difficult to copy the data. A similar problemoccurs where data in the first LU only is to be copied to another LU, orwhere data within the first and second LUs is to be copied to two otherLUs.

In this embodiment, on the other hand, since the integrated LU isestablished in the two memory areas, even where the actual data of afile is stored in the second memory area, the data pointer of the inodein the metadata does not include a LUN. Thus, in this embodiment, datain the integrated LU can be copied easily to another LU. That is, inthis embodiment, copying of data in filesystem units can be carried outmore easily compared with the comparative example.

Also, in this embodiment, since an integrated LU is established in thetwo memory areas, and a one filesystem is built on the integrated LU, itis easier to implement a snapshot function for creating an image of thefilesystem, as compared to the case where two LUs are established in thetwo memory areas, and two filesystems are built on the two LUs.

B. Second Embodiment:

FIG. 13 shows the structure of a filesystem on the first LU (LUN=0) inthe second embodiment, and corresponds to FIG. 8. In FIG. 13, blockgroups created in the second memory area are modified, as compared withFIG. 8. Specifically, in the second memory area, similar to the blockgroup established in the first memory area, there is created a blockgroup of the first type including an inode counter and an inode list,and capable of storing metadata.

In this embodiment, as in the first embodiment, creation of thefilesystem can be executed by the procedure depicted in FIG. 5. In thisembodiment, however, usages to the effect that metadata is stored inboth the first type of medium (FC) and the second type of medium (ATA),are specified. As a result, in this embodiment, the filesystem depictedin FIG. 13 is created within the first LU (LUN=0). Further, in thisembodiment, the content of the volume management table TB obtained inStep S114 differs from that in the first embodiment (FIG. 7).Specifically, in regard to the first LU (LUN=0), both the first memoryarea composed of the first type of medium (FC) and the second memoryarea composed of the second type of medium (ATA) is set to allow storageof metadata.

In this embodiment, new file creation can be executed according to theprocedure depicted in FIG. 9, as in the first embodiment. In thisembodiment, however, the block groups created in the integrated LU areall block groups of the first type capable of storing metadata, and sothe processes of Steps S203, S204, S206, and S210 may be omitted.

In FIG. 13, “file A” is stored in the same manner as in FIG. 8. On theother hand, while the actual data of “file B” is stored in “block group4” in the second memory area, as in FIG. 8, the metadata (i.e. thedirectory information and inode) pertaining to “file B” is stored within“block group 4” in the second memory area, in contrast to FIG. 8.

FIG. 14 is a flowchart depicting the procedure for transferring a filewithin the integrated LU in the second embodiment, and corresponds toFIG. 10. Note that, Steps S302, S310, and S312 of FIG. 14 are the sameas in FIG. 10.

In Step S306, the filesystem controller 126 creates an inode and writesthe actual data of the file targeted for transfer, in the transferdestination memory area. Note that, the process of Step S306 is similarto the process of Step S208 of FIG. 9.

Specifically, first, one block group is selected as a target blockgroup, from among one or more block groups created in the transferdestination memory area.

Next, in the target block group of the transfer destination memory area,a new inode area is acquired from the free data block list, and theaddress of the new inode area is registered in the inode list.

Next, in the target block group of the transfer destination memory area,a new data area is acquired from the free data block list, and theaddress of the new data area is registered in the data pointer of theinode. Then, the actual data of the target file for transfer is read outfrom the former data area of the transfer source memory area, andwritten to the new data area of the transfer destination memory area.

In Step S308, the filesystem controller 126 deletes the associationbetween the file name and the former inode, from the directoryinformation in the transfer source memory area. Specifically, theaforementioned association is deleted from the directory information inthe block group of the transfer source memory area, in which the targetfile for transfer remains stored.

In Step S308, the filesystem controller 126 frees up the former inodearea of the transfer source memory area, in which the inode of thetarget file for transfer remains stored. Specifically, in the blockgroup containing the former inode area, the former inode area is addedas the free areas to the free data block list. By so doing, it becomespossible to write other data to the former inode area.

In Step S310, the former data area of the transfer source memory area inwhich the actual data of the target file for transfer remains stored isreleased, in the manner described with reference to FIG. 10.

FIG. 15 shows the structure of the filesystem before and after the filetransfer process in the second embodiment. While FIG. 15 is similar toFIG. 13, a diagram of the data block interior after the transfer processis added.

In FIG. 15, “file A” is being transferred from the first memory areacomposed of the first type of medium (FC) to the second memory areacomposed of the second type of medium (ATA). After the transfer process,an association between “file A” and “inode2” is added to the directoryinformation within the second memory area, and the association between“file A” and “inode1” is deleted from the directory information withinthe first memory area. Additionally, a new inode area of “file A” isestablished within the second memory area, and the former inode area of“file A” is released from the first memory area. Further, a new dataarea of “file A” is established within the second memory area, and theformer data area of “file A” is released from the first memory area.

Similarly, where “file B” is transferred from the second memory areacomposed of the second type of medium (ATA) to the first memory areacomposed of the first type of medium (FC), after the transfer process,an association between “file B” and a new inode is added to thedirectory information within the first memory area, and the associationbetween “file B” and the former inode is deleted from the directoryinformation within the second memory area. Additionally, a new inodearea of “file B” is established within the first memory area, and theformer inode area of “file B” is released from the second memory area.Further, a new data area of “file B” is established within the firstmemory area, and the former data area of “file B” is released from thesecond memory area.

As described hereinabove, in this embodiment, as in the firstembodiment, one filesystem is built on an integrated LU. A plurality ofblock groups are then established in the integrated LU, but areestablished such that the each block group does not span the firstmemory area and second memory area. Thus, during creation of a new fileor file transfer, the actual data of the file is not stored spanning thefirst memory area and the second memory area (in other words, spanningthe first type of medium and the second type of medium), and within onefilesystem files are distributed to the first memory area or secondmemory area, in file units. Accordingly, files can be stored to theappropriate type of medium depending on their value, and as a result itis possible to utilize a plurality of types of media efficiently.

In this embodiment, like the first embodiment, capacity management,copying of data in filesystem units, and application of snapshotfunction can be carried out easily.

In particular, in this embodiment, block groups of a first type capableof storing metadata are established in both the first memory areacomposed of the relatively expensive first medium (FC) and the secondmemory area composed of the relatively inexpensive second medium (ATA).In the first embodiment, on the other hand, block groups of a first typecapable of storing metadata are established only in the relativelyexpensive first type of medium (FC). Thus, in this embodiment, theper-bit cost entailed in storage of metadata can be reduced incomparison to the first embodiment.

C. Third Embodiment:

FIG. 16 shows the structure of a filesystem on the first LU (LUN=0) inthe third embodiment, and corresponds to FIG. 8. In FIG. 16, block groupcreated on the first LU is modified, as compared to FIG. 8.Specifically, in the first LU, only a single block group (first type ofblock group) is created. That is, in this embodiment, there isestablished a block group that spans two memory areas.

However, as will be discussed later, in this embodiment, block groupplacement information and other such information other than data block(hereinafter termed “non-data block information”) is stored only in thefirst memory area. Also, while the data block spans two memory areas,metadata is stored only in the first memory area.

In this embodiment, as in the first embodiment, creation of thefilesystem may be executed according to the procedure depicted in FIG.5. As in the first embodiment, in this embodiment, there are specifiedusages to the effect that metadata is stored to the first type of medium(FC), and metadata is not stored to the second type of medium (ATA).Additionally, in this embodiment, there are specified usages to theeffect that only a single block group is created, and non-data blockinformation is stored to the first type of medium (FC) and is not storedto the second type of medium (ATA). As a result, in this embodiment, thefilesystem depicted in FIG. 16 is created in the first LU (LUN=0). Inthis embodiment, the content of the volume management table obtained inStep S114 is the same as that in the first embodiment (FIG. 7).

In the first and second embodiments, each block group is established soas to not span the two types of media. The free data block list of eachblock group is capable of assigning only free space in the address rangeof that particular block group, to the inode area and data area. Thatis, in the first and second embodiments, once a block group has beenselected depending on the type of medium for storage, and an inode areaand data area have been acquired from the corresponding free data blocklist, the areas will be areas composed of the intended type of medium.In this embodiment, however, the single block group is established so asto span the two types of media. Thus, in this embodiment, even where aninode area and data area have been acquired from the free data blocklist of the single block group, it will be unclear which of the types ofmedium make up the areas. Accordingly, in this embodiment, the new filecreation process and file transfer process are modified in the mannerdiscussed below. Specifically, in this embodiment, the starting addressand ending address of the “type of medium of the first memory area”(memory area capable of storing metadata) and the starting address andending address of the “type of medium of the second memory area” (memoryarea not capable of storing metadata) in the volume management table arerecognized and distinguished by the file server. By so doing, despitethe block group being established spanning two types of media, the fileserver can store a file in a specific area.

FIG. 17 is a flowchart depicting the procedure for creating a new filein an LU. While FIG. 17 is similar to FIG. 9, Steps S208C and S210C aremodified. In addition, if a negative decision is made in Step S203, theroutine proceeds to the same Step S208 as in FIG. 9.

Step S208C is executed if the storage destination LU is an integrated LUcomposed of multiple types of media, and the storage destination memoryarea is capable of storing metadata (e.g. where the storage destinationLU is the first LU (LUN=0) of FIG. 16, and the storage destinationmemory area is the first memory area composed of the first type ofmedium (FC)).

In Step S208C, the filesystem controller 126 creates an inode and writesthe actual data of the file to the storage destination memory area (e.g.the first memory area in FIG. 16).

Specifically, first, in the single block group of the integrated LU, anew inode area is acquired from the free data block list, and theaddress of the new inode area is registered in the inode list. It isnecessary that the new inode area be secured within a memory areacapable of storing metadata. Thus, the filesystem controller 126,referring to the volume management table TB, acquires as the new inodearea an area contained within the address range of a storage destinationmemory area capable of storing metadata.

Next, in the single block group of the integrated LU, a new data area isacquired from the free data block list, and the address of the new dataarea is registered in the data pointer of the inode. During thisprocess, the filesystem controller 126, referring to volume managementtable TB, acquires as the new data area an area contained within theaddress range of the storage destination memory area. The actual data ofthe file is then written to the new data area.

Step S210C, on the other hand, is executed if the storage destination LUis an integrated LU composed of multiple types of media, and the storagedestination memory area is not capable of storing metadata (e.g. wherethe storage destination LU is the first LU (LUN=0) of FIG. 16, and thestorage destination memory area is the second memory area composed ofthe second type of medium (ATA)).

In Step S210C, the filesystem controller 126 creates an inode in anothermemory area (e.g. the first memory area in FIG. 16) capable of storingmetadata but different from the storage destination memory area (e.g.the second memory area in FIG. 16), and write the actual data of thefile to the storage destination memory area

Specifically, first, in the single block group of the integrated LU, anew inode area is acquired from the free data block list, and theaddress of the new inode area is registered in the inode list. Duringthis process, the filesystem controller 126, referring to the volumemanagement table TB, acquires as the new inode area an area containedwithin the address range of the other memory area capable of storingmetadata.

Next, in the single block group of the integrated LU, a new data area isacquired from the free data block list, and the address of the new dataarea is registered in the data pointer of the inode. During thisprocess, the filesystem controller 126, referring to the volumemanagement table TB, acquires as the new data area an area containedwithin the address range of the storage destination memory area. Theactual data of the file is then written to the new data area.

In FIG. 16, as in FIG. 8, the actual data and metadata of “file A” arestored in the first memory area. Also, in the same manner as FIG. 8, theactual data and metadata of “file B” are stored in the second memoryarea. However, whereas in FIG. 8 the actual data and metadata of “fileB” are stored in different block groups, in FIG. 16 they are stored inthe single block group.

FIG. 18 is a flowchart depicting the procedure when transferring a filewithin the integrated LU in the third embodiment, and corresponds toFIG. 10. While FIG. 18 is similar to FIG. 10, Step S304C is modified.

In Step S304C, the filesystem controller 126 writes the actual data ofthe target file for transfer to the transfer destination memory area,and modifies the content of the inode corresponding to the target filefor transfer.

Specifically, in the single block group of the integrated LU, a new dataarea is acquired from the free data block list. During this process, thefilesystem controller 126, referring to the volume management table TB,acquires as the new data area an area contained within the address rangeof the transfer destination memory area. The address indicated by thedata pointer of the inode corresponding to the target file is modifiedfrom the address of the former data area to the address of the new dataarea.

The actual data of the target file for transfer is then read out fromthe former data area within the transfer source memory area, and iswritten to the new data area of the transfer destination memory area.

Note that, in Step S310, as described in FIG. 10, the former data areaof the transfer source memory area, in which the actual data of thetarget file for transfer still remains, is released.

FIG. 19 shows the structure of the filesystem before and after the filetransfer process in the third embodiment. While FIG. 19 is similar toFIG. 16, a diagram of the data block interior after the transfer processis added.

In FIG. 19, “file A” is being transferred from the first memory areacomposed of the first type of medium (FC) to the second memory areacomposed of the second type of medium (ATA). After the transfer process,there is established within the second memory area a new data areastoring the actual data of “file A”, while the former data area in whichthe actual data of “file A” was stored previously is released from thefirst memory area. The address indicated by the data pointer of “inode1”is modified from the address of the former data area to the address ofthe new data area. Note that, the directory information is not modified.

Similarly, where “file B” is being transferred from the second memoryarea composed of the second type of medium (ATA) to the first memoryarea composed of the first type of medium (FC), after the transferprocess, there is established within the first memory area a new dataarea storing the actual data of “file B”, while the former data area inwhich the actual data of “file B” was stored previously is released fromthe second memory area. The address indicated by the data pointer of“inode2” is modified from the address of the former data area to theaddress of the new data area. Note that, the directory information isnot modified.

In the above manner, in this embodiment as in the first embodiment,since metadata is stored only in the first memory area composed of thefirst type of medium (FC), when transferring a file, it is sufficient tomodify the metadata relating to the file, rather than creating it anew.

As described hereinabove, in this embodiment, as in the firstembodiment, one filesystem is built on an integrated LU. In thisembodiment, however, only a single block group is established within theintegrated LU, and the block group is established so as to span thefirst memory area and second memory area. Accordingly, in thisembodiment, by means of referring to the volume management table TB,metadata regarding to a file is stored in the first memory area only,while the actual data of the file is stored in one of the appropriatememory areas only. Thus, in this embodiment as well, when creating a newfile or transferring a file, the actual data of the file is not storedspanning the first memory area and the second memory area (in otherwords, spanning the first type of medium and the second type of medium),and within one filesystem files are distributed to the first memory areaor second memory area, in file units. Accordingly, files can be storedto the appropriate type of medium depending on their value, and as aresult it is possible to utilize multiple types of media efficiently.

In this embodiment, like first embodiment, capacity management, copyingof data in filesystem units, and application of snapshot function can becarried out easily.

In particular, in this embodiment, since a filesystem having structuresimilar to a general purpose filesystem is built on the integrated LU,there is the advantage that a client 400 can refer to the filesystembuilt in the storage unit 130 directly, without going through the fileserver 110.

The invention is not limited to the above examples and embodiments setforth hereinabove, and can be reduced to practice in various wayswithout departing from the spirit thereof, such as the followingvariations, for example.

(1) In the embodiments hereinabove, multiple memory areas composed ofmultiple types of media are integrated using functions of the storageunit 130 (more specifically, the second configuration manager 154), anda filesystem is built on the resultant integrated memory area(integrated LU). However, instead of this, another method may beemployed. For example, where the file server 110 is equipped with alogical volume manager (computer program), multiple memory areascomposed of multiple types of media may be integrated using functions ofthe logical volume manager, and a filesystem built on the resultantintegrated memory area. Alternatively, where a virtualization switch isutilized, multiple memory areas composed of multiple types of mediawithin a plurality of storage devices may be integrated using functionsof the virtualization switch, and a filesystem built on the resultantintegrated memory area.

Whereas in the preceding embodiments, an FC compatible hard disk and anATA compatible hard disk are used as media, other media may be used aswell. For example, an optical disk, magnetooptical disk, or magnetictape may be used as well.

In general, one filesystem will be built on an integrated memory areathat includes a first memory area composed of at least part of firsttype of storage medium and a second memory area composed of at leastpart of second type of storage medium.

(2) Whereas in the preceding embodiments, the file distributioncontroller 214 is disposed in the management server 200, it couldinstead be disposed in the file server 110. By so doing, during the newfile creation process (or file transfer process) the file server 110 candetermine the type of storage destination medium (or the target file fortransfer and the type of transfer destination medium).

Also, in the preceding embodiments the management server 200 comprisesthe file distribution controller 214, and the file server 110 receivesthe type of storage destination medium or target file for transfer etc.from the management server 200 during the new file creation process orfile transfer process (more specifically, in Step S204 or S302),respectively. But it could instead be designed that the file server 110receives a distribution rule from the management server.

Additionally, whereas in the preceding embodiments, during the new filecreation process the type of storage destination medium is determined bythe file distribution controller 214, the type of storage destinationmedium could instead be specified by the client 400, when the file issent by the client 400.

Also, whereas in the preceding embodiments, during the file transferprocess the target file for transfer etc. are determined by the filedistribution controller 214, the target file for transfer etc. couldinstead be specified by the client 400.

Whereas in the embodiments hereinabove, the management server 200 andthe management terminal 300 are constituted as different devices, thestorage system and the management terminal could be constituted as thesame device.

Although the present invention has been described and illustrated indetail, it is clearly understood that the same is by way of illustrationand example only and is not to be taken by way of limitation, the spiritand scope of the present invention being limited only by the terms ofthe appended claims.

1. A file server coupled to a storage unit having a plurality of storagemediums including at least one first type storage medium and at leastone second type storage medium of which access time is lower than accesstime of the at least one first type storage medium, the file servercomprising: a network interface for communicating with a clientcomputer; and a file manager for managing files stored in a plurality oflogical units corresponding to a plurality of file systems,respectively, in the storage unit, wherein the file manager configuresat least one file system of the plurality of file systems, in anintegrated logical unit including both the at least one first typestorage medium and the at least one second type storage medium, whereinthe network interface receives a first write request of a first file ofthe file system related to the integrated logical unit from the clientcomputer, the first file including first data and first metadata, thefirst metadata including a first file name and first inode information,wherein the file manager registers the first metadata of the first fileto the at least one first type storage medium, and writes the first dataof the first file to the at least one first type storage medium, whichare selected based on a distribution rule to be set depending on a filevalue, wherein the network interface receives a second write request ofa second file of the file system from the client computer, the secondfile including second data and second metadata, the second metadataincluding a second file name and second inode information, wherein thefile manager registers the second metadata of the second file to the atleast one first type storage medium, and writes the second data of thesecond file to the at least one second type storage medium, which areselected based on the distribution rule, wherein when a changed saidfile value of the first file in the integrated logical unit causesstorage of the first file within the at least one first type storagemedium to become conflicted with the distribution rule of the firstfile, the file manager moves the first data in the first file from theat least one first type storage medium to the at least one second typestorage medium within a same said integrated logical unit, and modifiesthe first metadata already stored in the at least one first type storagemedium, so as to point to a location of the actual data of the at leastone second type storage medium.
 2. The file server as claimed in claim1, wherein the distribution rule is established utilizing a file name,last update time of the file, file creator, period of time for with thefile is stored within the storage system, a current day of the week, ora current time of day.
 3. The file server as claimed in claim 1, whereinwith regard to the plurality of logical units and the plurality of filesystems, each logical unit is used exclusively by a single correspondingfile system.
 4. The file server as claimed in claim 1, wherein the filemanager configures the at least one file system of the plurality of filesystems, in the integrated logical unit to include both: a distributedfirst type storage medium formed of exclusive plural storage mediumportions of plural first type storage mediums, respectively; and, adistributed second type storage medium formed of exclusive pluralstorage medium portions of plural second type storage mediums,respectively.
 5. A file server coupled to a storage unit having aplurality of storage mediums including a first storage area configuredby at least one first type storage medium and a second storage areaconfigured by at least one second type storage medium of which accesstime is lower than access time of the at least one first type storagemedium, the file server comprising: a network interface forcommunicating with a client computer; and a file manager for managingfiles stored in a plurality of logical units corresponding to aplurality of file systems, respectively, in the storage unit, whereinthe file manager configures at least one file system of the plurality offile systems, in an integrated logical unit including both the firststorage area and the second storage area, wherein the network interfacereceives a first write request of a first file of the file systemrelated to the integrated logical unit from the client computer, thefirst file including first data and first metadata, the first metadataincluding a first file name and first inode information, wherein thefile manager selects the first storage area based on a distribution ruleto be set depending on a file value, and stores the first data to theselected first storage area, and registers the first metadata to thefirst storage area, wherein the network interface receives a secondwrite request of a second file of the file system from the clientcomputer, the second file including second data and second metadata, thesecond metadata including second file name and second inode information,and wherein the file manager selects the second storage area based onthe distribution rule, and stores the second data to the selected secondstorage area, and registers the second metadata to the first storagearea, wherein when a changed said file value of the first file in theintegrated logical unit causes storage of the first file within the atleast one first type storage medium to become conflicted with thedistribution rule of the first file, the file manager moves the firstdata in the first file from the at least one first type storage mediumto the at least one second type storage medium within a same saidintegrated logical unit, and modifies the first metadata already storedin the at least one first type storage medium, so as to point to alocation of the actual data of the at least one second type storagemedium.
 6. The file server as claimed in claim 5, wherein thedistribution rule is established utilizing a file name, last update timeof the file, file creator, period of time for with the file is storedwithin the storage system, a current day of the week, or a current timeof day.
 7. The file server as claimed in claim 5, wherein with regard tothe plurality of logical units and the plurality of file systems, eachlogical unit is used exclusively by a single corresponding file system.8. The file server as claimed in claim 5, wherein the file managerconfigures the at least one file system of the plurality of filesystems, in the integrated logical unit to include both: a distributedfirst type storage medium formed of exclusive plural storage mediumportions of plural first type storage mediums, respectively; and, adistributed second type storage medium formed of exclusive pluralstorage medium portions of plural second type storage mediums,respectively.
 9. A method useable within a file server coupled to astorage unit having a plurality of storage mediums including at leastone first type storage medium and at least one second type storagemedium of which access time is lower than access time of the at leastone first type storage medium, the method comprising: communicating witha client computer via a network interface; and managing files stored ina plurality of logical units corresponding to a plurality of filesystems, respectively, in the storage unit via a file manager,configuring at least one file system of the plurality of file systems,in an integrated logical unit which includes both the at least one firsttype storage medium and the at least one second type storage medium,receiving a first write request of a first file of the file systemrelated to the integrated logical unit from the client computer, thefirst file including first data and first metadata, the first metadataincluding a first file name and first inode information, registering thefirst metadata of the first file to the at least one first type storagemedium, writing the first data of the first file to the at least onefirst type storage medium which is selected based on a distribution ruleto be set depending on a file value, receiving a second write request ofa second file of the file system from the client computer, the secondfile including second data and second metadata, the second metadataincluding a second file name and second inode information, registeringthe second metadata of the second file to the at least one first typestorage medium, writing the second data of the second file to the atleast one second type storage medium, which is selected based on thedistribution rule, and wherein when a changed said file value of thefirst file in the integrated logical unit causes storage of the firstfile within the at least one first type storage medium to becomeconflicted with the distribution rule, moving the first data in thefirst file from the at least one first type storage medium to the atleast one second type storage medium within a same said integratedlogical unit, and modifying the first metadata already stored in the atleast one first type storage medium, so as to point to a location of theactual data of the at least one second type storage medium.
 10. A methoduseable within a file server coupled to a storage unit having aplurality of storage mediums including a first storage area configuredby at least one first type storage medium and a second storage areaconfigured by at least one second type storage medium of which accesstime is lower than access time of the at least one first type storagemedium, the method comprising: communicating with a client computer viaa network interface; and managing files stored in a plurality of logicalunits corresponding to a plurality of file systems, respectively, in thestorage unit via a file manager, configuring at least one file system ofthe plurality of file systems, in an integrated logical unit includingboth the first storage area and the second storage area, receiving afirst write request of a first file of the file system related to theintegrated logical unit from the client computer, the first fileincluding first data and first metadata, selecting the first storagearea for storing the first data of the first file based on adistribution rule to be set depending on a file value, storing the firstdata of the first file to the selected first storage area, registeringthe first metadata to the first storage area, receiving a second writerequest of a second file of the file system from the client computer,the second file including second data and second metadata, selecting thesecond storage area for storing the second data of the second file basedon the distribution rule, storing the second data of the second file tothe selected second storage area, registering the second metadata to thefirst storage area, wherein when a changed said file value of the firstfile in the integrated logical unit causes storage of the first filewithin the at least one first type storage medium to become conflictedwith the distribution rule of the first file, moving the first data inthe first file from the at least one first type storage medium to the atleast one second type storage medium within a same said integratedlogical unit, and modifying the first metadata already stored in the atleast one first type storage medium, so as to point to a location of theactual data of the at least one second type storage medium.